1. Technical Field
The present invention relates to a drive apparatus utilizing electromagnetic force. It also relates to an XY table that uses the drive apparatus as a drive source and that is used in apparatuses for the manufacture of semiconductors, for example.
2. Background Art
JP Patent Publication (Kokai) No. 2001-28875A discloses a drive apparatus used as a drive source in a conventional semiconductor manufacturing apparatus. In this example, a plurality of permanent magnets are disposed on a needle such that their directions of magnetization alternate. A stator includes two kinds of magnetic cores, and a plurality of armatures with coil windings are arranged in series. Another example of the drive apparatus is disclosed in JP Patent Publication (Kokai) No. 11-262237 A (1999), in which, for achieving higher accuracy in needle position control and in order to decrease thrust ripples, a position sensor for detecting the position of the needle is disposed toward the stator.
When a drive apparatus utilizing electromagnetic force is fitted with a magnetic pole position detector to achieve higher position control accuracy and reduce thrust ripples, for example, the overall size of the drive apparatus could become excessively large, possibly limiting the available location for its installation. This problem is particularly relevant in the case of using the drive apparatus as a drive source in apparatuses for manufacturing semiconductor-based electronic devices, for example, which are required to be as compact as possible.